Alumina slurry with high solid content and low viscosity and preparation method thereof

Abstract

The present invention proposes an alumina slurry with high solid content and low viscosity and a preparation method thereof, which relates to the field of alumina fiber composite materials, and the preparation steps include: preparing a lanthanum phosphate precursor solution; adding high-purity nano-alumina powder to the lanthanum phosphate precursor solution to obtain an alumina slurry with lanthanum phosphate; mixing the alumina slurry with lanthanum phosphate in a high-speed disperser, and then heating it to obtain a mixed system; after the mixed system is gelled, high-temperature sintering is performed to obtain a solid; deionized water is added to the solid and ball-milled to obtain an alumina slurry with high solid content and low viscosity. The present invention can solve the problem of low impregnation efficiency in the preparation process of alumina-based composite materials.

Description

Technical Field

[0001] The present invention relates to the field of alumina fiber composite materials, and in particular to a method for preparing alumina slurry with high solid content and low viscosity. Background Art

[0002] Alumina (Al 2 O 3 ) has excellent mechanical, thermal and optical properties. It can be used in fields such as engineering ceramics, gemstone industry and solid electrolytes. With the development of advanced composite materials and their application in high-tech fields, oxide ceramic fibers are increasingly valued.

[0003] Alumina fiber reinforced composite materials are an important application direction of alumina fiber. At present, the methods for preparing alumina fiber reinforced composite materials include impregnation and pulling method, sol-gel method, lamination hot pressing method, etc. These preparation methods generally require impregnation with alumina slurry first, but alumina slurry is not easy to gel and has a high viscosity when the solid content is high. When the solid content of the alumina slurry commonly used at present is greater than 50%, the viscosity of the slurry rises sharply to more than 50mpa·s, and the fluidity is poor, which is not conducive to impregnating fiber fabrics. Summary of the invention

[0004] Aiming at the problem of low impregnation efficiency in the preparation process of alumina-based composite materials, the present invention provides a high-solid-content, low-viscosity alumina slurry and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for preparing alumina slurry with high solid content and low viscosity comprises the following steps:

[0007] 1) preparing a lanthanum phosphate precursor solution;

[0008] 2) adding high-purity nano-alumina powder to the lanthanum phosphate precursor solution to obtain an alumina slurry containing lanthanum phosphate;

[0009] 3) mixing the alumina slurry with lanthanum phosphate evenly in a high-speed disperser, and then heating it to obtain a mixed system;

[0010] 4) After the mixed system is gelled, high temperature sintering is performed to obtain a solid;

[0011] 5) adding deionized water to the solid and ball milling to obtain alumina slurry with high solid content and low viscosity.

[0012] Preferably, the step of preparing the lanthanum phosphate precursor solution in step 1) comprises:

[0013] 60-80 parts by weight of lanthanum phosphate hexahydrate, 110-130 parts by weight of citric acid, and 220-260 parts by weight of deionized water are uniformly mixed, and then 80-100 parts by weight of ammonia water are slowly added dropwise to prepare a solution a;

[0014] Mix 10-15 parts by weight of phosphoric acid and 50-70 parts by weight of deionized water evenly, and then slowly add 5-10 parts by weight of ammonia water to prepare solution b;

[0015] The solution a and the solution b are placed in an ice water bath, and when the temperature of the two solutions is lower than 5° C., the two solutions are mixed to obtain a lanthanum phosphate precursor solution.

[0016] Preferably, the actual particle size of the high-purity nano-alumina powder in step 2) is between 10 and 100 nm.

[0017] Preferably, in step 2), the mass ratio of the high-purity nano-alumina powder to the lanthanum phosphate precursor solution is 10:1 to 15:1.

[0018] Preferably, the rotation speed of the high-speed disperser in step 3) is 2500-3000 r / min.

[0019] Preferably, the temperature of the heating treatment in step 3) is 60-80° C., and the treatment time is 5-8 hours.

[0020] Preferably, the high temperature sintering in step 4) is performed at a temperature of 850 to 1000° C. and for a time of 1 to 2 hours.

[0021] Preferably, in step 5), the mass ratio of the solid to the deionized water is 5:5 to 6:4.

[0022] Preferably, the ball milling speed in step 5) is 450-500 r / min; and the ball milling time is 4-5 h.

[0023] A high-solid content and low-viscosity aluminum oxide slurry is prepared by adopting the preparation method provided by the invention.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The method for preparing alumina slurry provided by the present invention prepares a lanthanum phosphate interface layer on the surface of alumina powder, coats the surface of alumina powder, modifies the surface of the powder, increases the distance between slurry molecules, significantly reduces the interaction force between multiple molecules, and can effectively improve the agglomeration effect between alumina powder particles, resulting in a better effect during impregnation.

[0026] (2) The alumina slurry provided by the present invention has the characteristics of high solid content and low viscosity. When the solid content reaches 60%, the viscosity value is only 25.4 mPa·s. Compared with the traditional alumina slurry, the impregnation efficiency is higher and the cost is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a physical photo of the alumina slurry prepared in Example 1. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the present invention, the present invention is further described below with reference to examples.

[0029] Embodiment 1:

[0030] 1. After 80 parts of lanthanum phosphate hexahydrate, 130 parts of citric acid, and 250 parts of deionized water are mixed evenly, 80 parts of ammonia water are slowly added dropwise to prepare solution a; 10 parts of phosphoric acid and 50 parts of deionized water are mixed evenly, and 5 parts of ammonia water are slowly added dropwise to prepare solution b; solution a and solution b are placed in an ice water bath, and when the temperature of solution a and solution b is lower than 5°C, solution a and solution b are mixed to obtain a lanthanum phosphate precursor solution;

[0031] 2. Add alumina powder to the lanthanum phosphate precursor solution at a mass ratio of 12:1, and use a high-speed disperser at 2500r / min to disperse the mixed system evenly;

[0032] 3. Place the mixed system in a constant temperature oven at 80°C for 5 hours;

[0033] 4. Place the gelled mixed system in a crucible and use a high-temperature sintering furnace at 900°C for 1 hour;

[0034] 5. Add the sintered solid and deionized water in a mass ratio of 6:4 into a ball mill and mill for 5 hours (milling speed 500 r / min).

[0035] Embodiment 2:

[0036] 1. After 70 parts by weight of lanthanum phosphate hexahydrate, 120 parts by weight of citric acid, and 260 parts by weight of deionized water are uniformly mixed, 90 parts by weight of ammonia water are slowly added dropwise to prepare solution a; 13 parts by weight of phosphoric acid and 60 parts by weight of deionized water are uniformly mixed, and 7 parts by weight of ammonia water are slowly added dropwise to prepare solution b; solution a and solution b are placed in an ice water bath, and when the temperature of solution a and solution b is lower than 5°C, solution a and solution b are mixed to obtain a lanthanum phosphate precursor solution;

[0037] 2. Add alumina powder to the lanthanum phosphate precursor solution at a mass ratio of 10:1, and use a high-speed disperser at 3000r / min to disperse the mixed system evenly;

[0038] 3. Place the mixed system in a constant temperature oven at 70°C for 6 hours;

[0039] 4. Place the gelled mixed system in a crucible and treat it in a high-temperature sintering furnace at 850°C for 2 hours;

[0040] 5. Add the sintered solid and deionized water in a ball mill at a mass ratio of 5:5 and ball mill for 5 hours (ball mill speed 450 r / min).

[0041] Embodiment 3:

[0042] 1. After 60 parts of lanthanum phosphate hexahydrate, 110 parts of citric acid, and 220 parts of deionized water are mixed evenly, 100 parts of ammonia water are slowly added to prepare solution a; 15 parts of phosphoric acid and 70 parts of deionized water are mixed evenly, and 10 parts of ammonia water are slowly added to prepare solution b; solution a and solution b are placed in an ice water bath, and when the temperature of solution a and solution b is lower than 5°C, solution a and solution b are mixed to obtain a lanthanum phosphate precursor solution;

[0043] 2. Add alumina powder to the lanthanum phosphate precursor solution at a mass ratio of 15:1, and use a high-speed disperser at 2800r / min to disperse the mixed system evenly;

[0044] 3. Place the mixed system in a constant temperature oven at 60°C for 8 hours;

[0045] 4. Place the gelled mixed system in a crucible and use a high-temperature sintering furnace at 1000°C for 1 hour;

[0046] 5. Add the sintered solid and deionized water in a mass ratio of 6:4 into a ball mill and mill for 4 hours (ball mill speed 500 r / min).

[0047] Comparative Example 1:

[0048] Untreated alumina powder and deionized water were added to a ball mill at a mass ratio of 6:4 and then ball milled for 5 hours (ball milling speed of 500 r / min).

[0049] Comparative Example 2:

[0050] Untreated alumina powder and deionized water were added to a ball mill at a mass ratio of 5:5 and then ball milled for 5 hours (ball milling speed of 500 r / min).

[0051] Table 1 Main properties of the prepared alumina slurry

[0052] Solid content Viscosity Time for precipitation to occur Example 1 60％ 25.4mpa·s 38 days Example 2 50％ 6.2mpa·s 50 days Example 3 60％ 24.8mpa·s 37 days Comparative Example 1 60％ 105.8mpa·s 5 days Comparative Example 2 50％ 56.8mpa·s 30 days

[0053] It can be seen from Table 1 that the alumina slurry prepared from the treated alumina powder has lower viscosity at the same solid content, better stability, and can be stored for a longer time. When the untreated alumina powder is used to prepare the slurry, when the solid content is greater than 60%, the viscosity rises sharply to greater than 100mpa·s, which can no longer meet the impregnation requirements. When the treated alumina powder is formulated into a slurry with a solid content of 60%, the viscosity is only about 25mpa·s, and the fluidity is still good, and it can be used for impregnation; this is because the surface of the treated alumina powder is covered with a lanthanum phosphate interface layer, and the powders are not easy to agglomerate, so the slurry has better fluidity and stability.

[0054] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A method for preparing alumina slurry with high solid content and low viscosity, characterized in that: The following steps are involved: 1) Preparation of lanthanum phosphate precursor solution 60-80 parts by weight of lanthanum phosphate hexahydrate, 110-130 parts by weight of citric acid, and 220-260 parts by weight of deionized water are uniformly mixed, and then 80-100 parts by weight of ammonia water are slowly added dropwise to prepare a solution a; Mix 10-15 parts by mass of phosphoric acid and 50-70 parts by mass of deionized water, and then slowly add 5-10 parts by mass of ammonia water to prepare solution b; placing the solution a and the solution b in an ice water bath, and mixing the two solutions when the temperature is lower than 5° C. to obtain a lanthanum phosphate precursor solution; 2) adding high-purity nano-alumina powder to the lanthanum phosphate precursor solution to obtain an alumina slurry containing lanthanum phosphate; the mass ratio of the high-purity nano-alumina powder to the lanthanum phosphate precursor solution is 10:1 to 15:1; 3) mixing the alumina slurry with lanthanum phosphate uniformly in a high-speed disperser, and then heating it to obtain a mixed system; 4) After the mixed system is gelled, high temperature sintering is performed to obtain a solid; 5) adding deionized water to the solid and ball milling to obtain alumina slurry with high solid content and low viscosity.

2. The preparation method according to claim 1, characterized in that The actual particle size of the high-purity nano-alumina powder in step 2) is between 10 and 100 nm.

3. The preparation method according to claim 1, characterized in that: The rotation speed of the high-speed disperser in step 3) is 2500-3000 r / min.

4. The preparation method according to claim 1, characterized in that: The temperature of the heating treatment in step 3) is 60-80°C, and the treatment time is 5-8h.

5. The preparation method according to claim 1, characterized in that: The high temperature sintering in step 4) has a treatment temperature of 850-1000° C. and a treatment time of 1-2 hours.

6. The preparation method according to claim 1, characterized in that: In step 5), the mass ratio of the solid to the deionized water is 5:5 to 6:

4.

7. The preparation method according to claim 1, characterized in that: The ball milling speed in step 5) is 450-500 r / min; the ball milling time is 4-5 h.

8. A high solid content and low viscosity alumina slurry, characterized in that: The method is prepared by the method according to any one of claims 1 to 7.

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